Hi, You could use Shard-Query. You don't need to shard the database, you can point shard-query at one database. It supports WINDOW functions.
select date, FIRST_VALUE(value) OVER (ORDER BY value ASC), LAST_VALUE(value) OVER (ORDER BY value ASC) FROM some_table AS a GROUP BY date --Justin On Fri, Oct 2, 2015 at 6:12 PM, Roberto Spadim <[email protected]> wrote: > Hi guys > I have a problem and a possible solution, that i think is relative easy to > develop (i didn't tested but i think the source is easy to change) > > i have some queries like: > > > SELECT > date, > (SELECT value FROM some_table WHERE date=a.date ORDER BY date ASC LIMIT 1) > AS first, > (SELECT value FROM some_table WHERE date=a.date ORDER BY date DESC LIMIT > 1) AS last > FROM some_table AS a > GROUP BY date > > > i want to "convert" the complex sub query, to a agregate function, and i > thinking about group concat: > from mysql docs: > > GROUP_CONCAT([DISTINCT] *expr* [,*expr* ...] > [ORDER BY {*unsigned_integer* | *col_name* | *expr*} > [ASC | DESC] [,*col_name* ...]] > [SEPARATOR *str_val*]) > > > we have ORDER BY > if we could include a "LIMIT" clause, i could rewrite this query to: > > SELECT > date, > GROUP_CONCAT(value ORDER BY date ASC LIMIT 1) AS first, > GROUP_CONCAT(value ORDER BY date DESC LIMIT 1) AS last > FROM some_table AS a > GROUP BY date > > > i know that i could have stats tables / materialized views (with flexview, > i already tested :) ), but i want something more "easy to use" and not > "very fast", just a "feature" to solve small problems > > > it's a nice idea? does anyone have this "problem" and solve with other > solutions? > > -- > Roberto Spadim > > _______________________________________________ > Mailing list: https://launchpad.net/~maria-discuss > Post to : [email protected] > Unsubscribe : https://launchpad.net/~maria-discuss > More help : https://help.launchpad.net/ListHelp > >
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